1. Field of the Invention
The present invention relates to production of slide fasteners for trousers, and more particularly to a method of and apparatus for feeding a continuous slide fastener chain with successive fly strips while various finishing steps, such as threading sliders and attaching bottom steps, is successively taking place on the slide fastener chain to provide slide fasteners of a predetermined length each having a fly strip.
2. Description of the Prior Art
In the manufacture of trousers, it has been customary to use, a continuous slide fastener chain to which successive fly strips are attached at equal distances by sewing the individual fly strips onto a tape of one of opposed stringers. Each fly strip is a prospective closure for a front fly opening of the trousers. At the start of a series of finishing steps, each fly strip is folded on such one stringer tape so that the resulting slide fastener chain has a difference in thickness between the opposed stringers. Because of this thickness difference, the slide fastener chain cannot be fed along a straight path as it passes a pair of vertically opposed feed rollers. Yet, if the slide fastener chain is fed in and along an elongated guide, twisting stresses would act on the slide fastener chain so as to cause the folded flies to become disarranged.
A solution has been proposed in Japanese Patent Laid-Open Publication No. 60-85704, in which a pair of vertically opposed feed rollers, one of which is driven, has upper and lower toothed wheels, respectively, for meshing engagement with a pair of coupled rows of fastener elements of the opposed stringers during the feeding of the slide fastener chain. The upper roller is adapted to be raised away from the lower roller to allow an individual slider on the slide fastener chain to pass the two feed rollers. However, a primary problem with this prior art apparatus is that the toothed wheels would be often brought out of meshing engagement of the fastener elements, thus causing an irregular feeding of the slide fastener chain.